I THINK!! (dont take this to heart as im not the fat burning guru you seek, look to allen or gram, lol) that the hr for fat burning is low bc they assume you will be doing it for a long time..

the point of hiit is to get the hr high high up there and then let it come down a little, and put it right back up there.. then after ur hr will stay high and continue burning fat after you've finished!(for ~20 min)

I think the whole heart-rate stuff is nonsense. Especially when talking about HIIT. The whole purpose of HIIT is to get your heart-rate up, up, up - so that it boosts your metabolism far more than doing steady-state cardio where your heart-rate is only at, say, 130.

I THINK!! (dont take this to heart as im not the fat burning guru you seek, look to allen or gram, lol) that the hr for fat burning is low bc they assume you will be doing it for a long time..

the point of hiit is to get the hr high high up there and then let it come down a little, and put it right back up there.. then after ur hr will stay high and continue burning fat after you've finished!(for ~20 min)

Your sort of right Mreik, The theory behind it is

Fat is a lazy tissue, therefore a slower, steadier heart rate will supposedly use fat for energy rather than glucose.

Personally , I think its bull**** and a ploy to get people to buy a bike/elliptical/treadmill. Lets look at the facts.

1. Lets assume John Doe walks into a fitness equipment store and knows nothing about fitness. He sees treadmill A that tells him he should work around 160, and treadmill b that says he needs to work out at 130, knowing human beings on average tend to be a bit lazy (until they get motivated, then there's nothing on the planet that can stop them). Which one do you think he's going to buy?

/end conspiracy theory thinking

2. Have you ever done exercise that keeps your heart rate at 130? I have. Its not hard. Even though this machine is telling me Im burning fat, I'm getting no other benefit from it (if Im actually burning fat at all). Im not at the gym to spin my wheels, Im there to work, to better myself.

3. The benefits of working at 160 as opposed to 130 are paramount. You get cardio condtioning as well as fat burn. Add HIIT in the mix (running wise) and you get 3 fold results (cardio, fat burn, and VO2Max capacity increase, thats why I love it so much).

THis next comment isn't a slam, its the truth sadly

How many overweight people do you see at the gym plodding slowly away on a machine week after week that don't change ? I see them all the time. I can bet their heart rate is around their "fat burning" zone. It may work at first, but it stops working.

Wolverine, what your doing is HIIT, your not really entering a fat burning zone. That zone is supposedly meant for sustained work in that range. What your doing (and I think Spock and Mreik would agree with me) is your putting your cardio into overdrive, which is good.

then repeat. Work your way up to 10 intervals (if you can do them at first, thats great , work up the intensity of the high ones instead of adding more). After 10, 5 minutes cooldown. (warmup and cooldown are very important)

good to know! Thanks for the help. and I love this idea:
warm up for 5 minutes
do 1 minute high intensity interval
1 minute moderate intensity interval
But I thinking, how about 4 minutes for low intensity, and then the 1 min high intensity interval 1 min moderate intensity interval?

If not doing HIIT, then that appears to be right.You want to keep doing something contineous, while keeping the rate at a STABLE pace. ie..... 130 bpm for 20 min wont cut it, you need at least 45-60 min for that to be effective.

I'm SOOO confused!

This heartrate thread has me confused. Granted, I'm a newcomer to this whole thing having sat on my azz for 10 yrs and gaining 50 lbs. The doctor said you have arthritis in your knees and the next day I joined a local gym and have been going for a month now. (3 days on, 1 day off, etc.) --- On my way there now in a few actually --- Anyway, I've been doing 30-40 minutes on the cable weights with emphasis on thighs, arms and gut. Then 40 min on a treadmill. I go 3 minutes at zero incline, 2.9 on the speed until I'm warmed up, then 15 minutes at 3.0 incline at 3.2 on the speed, then when this really great song comes up on the mp3 player which is 4:54 minutes long, I pump up the incline to 11 or 12 and keep the speed at about the same. I get my HR up to about 155 and it feels great, but I can't maintain it for more than the song. When the song is over, I drop the incline back to 3, keep the speed the same, and my HR drops into the low 130's. I repeat the above until my time is up and then cool down for 3-5 minutes and my HR drops to 128ish. I've lost 8 lbs since I've started this, following a low calorie, high protein diet. BUTT (no pun intended) if I can do more, to keep 1-2 lbs rolling off each week -- I'm ON IT! Any advice? Comments?

A lot of what Aevans said is true, though I do disagree with one point. When you see those obese people plodding away on the treadmill, it may be that what they are doing IS high intensity for them. Or, it may very likely be that thier doctor has ordered them to keep thier heart rate under a certain level. For them to perform what you would consider high intensity could very well kill them.

The whole "Fat burning zone" thing is a bit deceiving. The reason it is displayed like that is this: Fat is your bodys most efficient source of energy, but it is also the most difficult to break down. During high intensity exercise, the demand for energy is too great for lipolysis to supply the demand. It still occurs, but at a reduced capacity, the breakdown of carbs is a much faster process.

When exercising in the "fat burning zone" you will burn a higher concentration of fat as opposed to other energy sources. The catch is, because you are exercising at a lower intensity, fewer total calories are burned. You also miss out on the increased metabolic effects of high intensity work, post training. Lets take a look at some of the pro's and cons.

Low intensity cardio:
Pros:
1) Higher concentration of fat burned, up to 70% as opposed to around 20% in high intensity exercise.
2) An over-all increase in fat mobilizing enzymes.
3) Easy on the joints.
4) Decreased muscle catabolization.
5) Mild increase in aerobic capacity.
Cons:
1) Fewer total calories burned than high intensity exercise.
2) Decreased hormonal response to exercise. (Endorphines, adrenaline, cortisol, can all help reduce body fat.)
3) Long and frequent sessions required to see effects.

High intensity cardio:
Pros:
1) Notable increases in aerobic capacity largely due to the strengthening of the heart.
2) Higher number of total calories burned. Although most of them are from glycogen stores, this is still a good thing since unused glycogen will be stored as fat.
3) Not much time needed to perform.
4) Hormonal response keeps burning calories at an increased level for up to 2 hours after exercise, depending on your time and intensity.
Cons:
1) Lower concentraion of fat burned during exercise. This is somewhat inconsequential due to the after effects.
2) Hormonal response includes increased cortisol levels, which catabolize proteins as well as fats to meet the high energy demand.
3) Can irritate sensitive joints. Chronic joint pain can occur if done too often, or without proper nutrition.

Both types are beneficial, most of the controversy exists because people will nearly always choose the one they enjoy more, and want to believe that it is the right way to do it. Both ways should be done and everything in between. All types of cardio are good, and beneficial to everyone.